1. Field of the Invention
The invention relates to an automotive electrical connection box.
2. Description of the Related Art
JP 10-302887 and FIG. 6 herein disclose an automotive electrical connection box. With reference to FIG. 6, the electrical connection box has lower and upper casings 1, 2 with surrounding walls that are lockingly coupled together with a lower cover 3. Connectors 4 are provided on the lower cover 3. A bolt B is introduced through the casings 1, 2 and is screwed into a bolt inserting portion 5 in the middle of connectors 4 in the lower cover 3. Thus, the casings 1, 2 are locked together and are fixed to the lower cover 3.
The bolt B can be unthreaded to release the casings 1, 2 from the lower cover 3. However, the casings 1, 2 are not raised automatically and detached from the lower cover 3 as the bolt B is unthreaded. Rather, an operator has to detach the casings 1, 2 from the lower cover 3 after the bolt B is unthreaded, thereby increasing operation steps.
The bolt B is not assembled with the casings 1, 2 beforehand. Rather, the bolt B must be inserted through the casings 1, 2 later to fix the casings 1, 2 to the lower cover 3. This subsequent insertion of the bolt B presents a parts administration problem.
FIG. 7 shows an electrical connection box that has been proposed to address the above-described problems. The electrical connection box of FIG. 7 has lower and upper casings 1, 2 with surrounding walls that are coupled together by locks. The lower casing 1 has a bolt hole and a collar 7 extends from the peripheral edge of a bolt hole. A flange 7a is defined on the collar 7. The upper casing 2 is formed integrally with a bolt inserting portion 2a. A small hole 2a-1 is formed in an upper part of the bolt inserting portion 2a and a large hole 2a-2 is formed in a lower part of the bolt inserting portion 2a. Thus, a downwardly facing step is defined in the bolt insertion portion 2a between the small hole 2a-1 the large hole 2a-2.
A bolt B is assembled with the casings 1, 2 to mount the assembled casings 1, 2 to a fixing member 6, such as a vehicle body, a holder or a lower cover. The bolt B is introduced through the collar 7 of the lower casing 1 and into the bolt inserting portion 2a of the upper casing 2. The large hole 2a-2 of the bolt inserting portion 2a surrounds the outer circumferential surface of a head Ba the bolt B with a specified clearance. However, the upper surface of the bolt head Ba contacts the downwardly facing step between the small and large holes 2a-1, 2a-2. Thus, the upper and lower surfaces of the head Ba are held rotatably between the downwardly facing step of the bolt insertion portion 2a and the upper end surface of the flange 7a of the collar 7.
The head Ba of the bolt B is exposed upwardly at the small hole 2a-1. Thus, an impact wrench (not shown) can be inserted into the bolt inserting portion 2a of the upper casing 2 from above. The impact wrench can engage the head Ba to screw the bolt B into a nut N embedded in the fixing member 6, thereby fixing the lower and upper casings 1, 2 to the fixing member 6.
The lower and upper casings 1, 2 can be detached from the fixing member 6 by inserting the impact wrench into the bolt inserting portion 2a of the upper casing 2. The bolt head Ba then is turned in a reverse direction to disengage the bolt B from the nut N. As a result, the upper end surface of the bolt head Ba pushes up on the downwardly facing step between the small hole 2a-1 and the large hole 2a-2 of the upper casing 2. Thus, the upper casing 2 is moved up and away from the fixing member 6. The surrounding walls of the lower and upper casings 1, 2 are locked together, and hence the lower casing 1 moves up with the upper casing 2. Accordingly, the lower and upper casings 1, 2 can be detached integrally from the fixing member 6.
The single bolt B in the middle of the casings 1, 2 is spaced from the locks on the surrounding walls. Forces exerted by the bolt B act on a middle part of the upper casing 2, but do not act over the entire upper casing 2. Accordingly, a part of the upper casing 2 near the bolt B deforms up. This deformation may cause the locks on the surrounding walls to disengage from the lower casing 1. Thus, only the upper casing 2 may detach with the bolt B, leaving the lower casing 1 on the fixing member 6.
The casings 1, 2 are locked only at the surrounding walls. Thus, the middles of the casings 1, 2 are likely to shake if the casings are large.
The invention was developed in view of the above problems, and an object is to improve operability during the mounting/dismounting of the electrical connection box to a holder or a body of a vehicle body.